This invention relates to a wheelchair ramp for a minivan and, in particular, to a battery powered ramp that can be extended or retracted easily even when there is no battery power available.
It is known in the art to provide a ramp for enabling a person in a wheelchair to enter or leave a vehicle. Trucks, buses, and large vans have a high ground clearance and are typically provided with a lifting mechanism to augment a ramp, which would be too long or too steep otherwise. The ramp in such mechanisms merely provides a gradual transition from the ground to the height of a platform that is raised or lowered. A type of light truck known as a minivan has a lower ground clearance than larger vehicles. Thus, a ramp can be used without a lift and the ramp typically folds in half when stored.
In the prior art, minivans are typically provided with a battery powered, folding ramp having a plurality of interlocks to prevent improper usage. For example, if the side door of a minivan is not opened fully, the ramp is prevented from extending. As long as power is available, ramps of the prior art work reliably and well. In the event of a power failure, the operation of known ramps leaves much to be desired.
In the prior art, it is generally assumed that a power failure occurs with a person in the minivan and that exiting the vehicle is all-important. Typically, a release mechanism is provided for extending the ramp after the door is opened. The ramp free-falls into an open position, creating a dangerous situation for someone standing near the open door. Often, the ramp free-falls quickly enough that the cabling used to extend the ramp does not operate properly and the end of the ramp slams into the ground at a steep angle and must be re-positioned manually. A folding metal ramp is heavy and cannot be handled by a person sitting in a wheelchair. Even for someone able to move about freely, a folding ramp is difficult to handle and it is preferred that two people control the ramp.
In the event of a power failure, it is not simply a matter of extending or retracting the ramp manually. The manual release mechanism in the mechanical drive for the ramp must be re-set. This usually requires some reassembly of the mechanical drive. Thus, for example, a power failure due to a blown fuse has the effect of stranding a wheelchair bound person or at least greatly delaying his travel while the system is restored to working order.
While there are many obvious solutions to the problem, such as a back-up power supply, one must realize that a ramp and a drive mechanism must fit an existing vehicle, i.e. a ramp is designed for the vehicle, not the other way around. A minivan is, by definition, a small van. Thus, most solutions to the problem are either too big, too expensive, or simply impractical. One wants to modify a minivan in a way that changes the finished appearance of the minivan as little as possible. Finding a location where a second battery, and the associated switching and charging apparatus, is both hidden and accessible is not easy in a minivan and is more difficult in a minivan that has already been heavily modified to accommodate a powered ramp. Similarly, any other solution to the problem must fit within commercially available vehicles without significantly affecting the space available for passengers or cargo.
In view of the foregoing, it is therefore an object of the invention to provide an electrically powered ramp that can be extended or retracted easily even when there is no electricity available.
Another object of the invention is to provide a compact drive mechanism for a ramp for a minivan, wherein the drive mechanism for the ramp is as unobtrusive as possible within the minivan.
A further object of the invention is to provide a compact drive mechanism for a ramp wherein the mechanism stores energy for raising and lowering the ramp without electrical power.
Another object of the invention is to reduce the electrical power required to raise and lower a powered ramp for a minivan.
A further object of the invention is to prevent a powered folding ramp from free-falling open in the event of a power failure.
Another object is to provide a controlled operation of a folding, powered ramp when power is interrupted.
A further object of the invention is to provide a powered ramp that can be operated manually or electrically at the discretion of the user.
Another object of the invention is to provide a powered ramp that can be operated part-way electrically and then operated manually, or vice-versa, from any point in the movement of the ramp.